The present invention relates generally to envelopes and, more particularly, to an envelope having a single peel-off backing sheet having strips of pressure sensitive adhesive located along the sides of a panel of the envelope, which facilitates processing through automatic mechanical sheet feed printing equipment, laser printing equipment and feed through copy machines prior to folding the panel in order to form an envelope. The single peel-off backing sheet preferably has a silicone coating on only one side which allows a person to print or write on the other side of the backing sheet. As such, the backing sheet may be used as stationery or a letter which may be placed inside the envelope.
In the past, difficulties have resulted in attempts to process envelopes through automatic mechanical printing equipment, laser printing equipment and copying machines because the envelopes were not of uniform thickness when folded as a result of overlapping closure flaps or other overlapping portions of the envelopes, or due to peel-off or release strips used to cover pressure sensitive adhesives or other types of adhesives in order to prevent the adhesives from being activated during high printing temperatures. For example, U.S. Pat. No. 4,715,531 discloses an envelope using a number of release strips to cover strips of adhesive, which leads to an envelope of variable thickness that causes problems during copying and printing.